Telephonic receiver.



A. H. NICHOLSON, TELEPHONIG RECEIVER.

APPLIOATION FILED snr'r. 2,1908.

Patented Feb. 16, 1909.

2 SHEETS-SHEET 1.

I 0 a a II 1 L WITNESSES INVENTOR G. H-YYKXMQW, mewme fume,

m a. 4% g 24% M M WQH A. H. NICHOLSON.

TELBPHONIG RECEIVER.

APPLIOATION FILED SEPT. 2,1908.

912,878. Patented Feb. 16, 1909.

2 SHEETS-SHEET 2.

WITNESSES INVEN'I'OR To all wlumt it may concern:

UNITED STATES PATENT OFFICE.

ARTHUR HAROLD NICHOLSON, or WENDOVER, ENGLAND, ASSIGNOR TO THE NEW PHONOPORE TELEPHONE COMPANY, LIMITED, OF LONDON, ENGLAND.

rnmenomc RECEIVER.

Be it known that LARTHUR HAROLD N1011- oLsoN, a subject of the King of Great Britain, residing at 5 Chiltern road, \Vendover, in the county of Bucks, England, electrical en 'ineer, have invented certain new and usefuf Improvements in Telephonic Receivers, of which the following is a s ecification..

A well known form of telep onic receiver comprises two parallel diaphragms between the poles of a permanent horseshoe magnet, a bar electromagnet being arranged between the diaphragms and included in the line or speaking circuit. The diaphragms form the ends of a drum held between the poles of the permanent magnet and the ends of the bobbin that carries the winding of the electromagnet are of the same diameter as the internal diameter of the drum; the periphery of these ends is cut away to allow of perforations through the part of the periphery of the casing at which the ear-piece is fixed, so that there may be communication between the recesses at the inner faces of the diaphragms and the ear-piece. By my invention such a receiver may be made more ef ficient and at the same time may be more easily and cheaply constructed if the arrangement illustrated in the accompanying drawings be adopted.

Figure 1 1s a sectlon through the receiver,

Fig. 2 is a plan, Fig. 3 an end view with parts removed and Figs. 4, 5 and 6 are detail views.

a is the permanent horseshoe magnet, b are its pole pieces, 0 are the diaphragms, d is the bar electromagnet of which e is the winding and f are the bobbin ends of insulating material.

The casing is made in three parts, a. central ring 9 and two end pieces h and 2', the diaphragms being held between the end pieces and the central ring.

The bobbin is fitted in a metal sleeve 70 which itself fits in'a circular wedge Zof suitable insulating material. This wedge is shown in side elevation, front elevation and plan in Fig. 4. This wedge, holding the bobbin, is fixed in the casing 1n such a position that the narrow part of the wedge is next the cir- Specification of Letters Patent. 9 Application filed September 2, 1908. Serial No. 451,462.

Patented Feb. 1'6, 1909.

phragms and a circular wedge-shaped piece carrying the bar electromagnet.

2. A telephone receiver comprising a permanent horseshoe magnet, two parallel diaphragms between the poles of this magnet, a

circu ar wedge shaped piece between the said diaphragms, a bar electromagnet and a perforation in the said wed e shaped iece adapted to receive the bobbin of the sai bar electroma net.

3. A t ephone receiver comprising a permanent horseshoe magnet, oppositely arranged 'pole pieces to the said magnet, a casing situated co-axially between the said pole pieces, two diaphragms within the said caslng, a circular wedge shaped piece between the said diaphragms, a central perforation in' the said wedge shaped piece-, a sleeve within the said perforation, and a bar electromagnet the bobbin of which fits in the said sleeve.

4. A telephone receiver comprising a permanent horseshoe magnet, a cylindrical casing situated between the poles of the said magnet, an opening in the periphery of the said casing, two diaphragms within the said casing, a circular wedge shaped piece between the two diaphragms having itsnarrower end next to the said opening and a bar electromagnet carried by the said circular wedge shaped piece.

5. A telephone receiver comprising a permanent horseshoe magnet, oppositely arranged pole pieces to the said magnet, a casing situated co-axially between the said pole pieces and consisting of a central ring and two end pieces, a diaphragm clamped between each end piece and the central ring, an opening in the periphery of the said ring,

said diaphragm having its narrower edge name to this specification in the presence of nextti1 the said opening, adcentil'lal perforation two subscribing witnesses.

in' e. sai circu ar We e s a ed piece, a

sleeve fitting the said pei i'oratio il and a bat ARTHUR HAROLD MCHOLSM' electromagnet having its bobbin fitting the Witnesses:

said sleeve. EDWARD 'GARDNER,

In testimony whereof I have signed my WALTER I. SKERTEN. 

